When working in the field of da'wah or other places, it may be necessary to have contact with the other gender to delegate tasks etc. Shaykh Dr. Haitham al-Haddad explains that this is allowed in a limited form when it is necessary, without getting involved in casual talk. But the Shaykh gives a severe warning to be very careful and not go over the limits as it have in many cases resulted in haram relationships among practising Muslims. Listen to the Shaykh explain the matter in detail in this video.